Su-Chi

Most creatures of its era died and left nothing behind; this one hands its controller four mana on the way out, turning every combat trade and removal spell into a mana-neutral exchange rather than a clean loss. That refund is the whole card, and it predates the dedicated colorless symbol: the trigger originally produced generic mana, and the wording has been errata'd forward through successive rules iterations so it keeps generating four of whatever the current era calls colorless. The body itself was aggressively sized for a 1994 artifact creature, a 4/4 that any deck could run because nothing about it was tied to a color, but the death trigger is why the card is remembered. Pair it with a free sacrifice outlet and a way to return it to play, and the trigger stops being a consolation prize and becomes the engine itself. Note the discipline in the math, though: a four-mana refund only funds another casting at break-even, so the loop needs a recursion source cheaper than four mana to net anything. That is exactly why the card lived alongside enablers like Goblin Welder and Tinker rather than functioning as a standalone combo piece. It is a clean statement of what Antiquities was doing with artifact creatures: bodies whose printed rate told only half the story, and whose death was as much a resource as their life.